Many eyeglass lenses are manufactured today from polymeric materials, including polycarbonate material. Polymeric or plastic lenses are preferred by consumers in part because of their reduced weight, which increases user comfort when the eyeglasses need to be worn for an extended period. The lens blank is frequently cast in circular configuration, so that each blank needs to be edged, or shaped, to size in order to thereafter be mounted in the frame which has been selected. A further requirement is that a safety bevel be formed about the lens, particularly adjacent the wearer.
Eyeglass frames have two spaced openings in which the finished lenses are mounted. The lens openings come in any number of sizes and configurations. Because there is no standard shape or size, nor a standard prescription, then the optician must shape each lens in a machine, known as an edger, preparatory to fitting the lens into the frame opening.
The frame openings frequently have a bevel or a groove which interfits with a complementarily shaped groove or bevel, respectively, formed about the peripheral edge of the lens. The interfit between the complementary bevel and groove helps to secure the lens within the opening, thereby preventing removal as otherwise could occur. The edging machine forms the bevel or groove about the lens. The position of the bevel or groove is not necessarily fixed relative to the front or back surfaces of the lens, so the edging machine may need to take into account not only formation of the bevel or groove but also where that bevel or groove is to be positioned intermediate the lens surfaces.
Some eyeglass frames have openings which do not completely encircle the lens. The bevel or groove is still provided in order to snap into the frame position, and the bevel or groove is continuous about the lens edge. When a lens is edged, the resulting edge will frequently have a smokey appearance caused by microscopic grooves scored into the edge by the grinding or cutting tool. The smokey finish is undesirable for those frames which have an opening not completely encircling the lens, and the smokey finish should be removed. Polishing is one technique used to remove this smokey finish in order for the finished lens to be acceptable to the user.
The lens edge may be polished through various means in order to remove the smokey finish. Removal of the lens from the edger to permit polishing on a subsequent machine is inconvenient, both because of increased cost and the possibility of loss, damage, or the like, to the lens. Polishing is one of the last steps prior to placing the lens into the frame, so damage to the lens is to be avoided because of the costs already accrued in forming the lens.
Edging of the lens, whether made of glass or polymeric material, can result in a sharp corner at the intersection of the inner surface and the peripheral edge. The sharp corner may present a safety concern, and therefore should be removed. A bevel may be ground about the lens in order to remove the sharp corner, thus forming an angled surface known as a safety bevel.
The disclosed invention is a dry edger which utilizes a two-part combination tool for edging the lens to an initial predetermined size and configuration with a first part of the tool, thereafter with a second part of that same tool completing the edging and size reduction process through a diamond bonded polishing tool which removes the smokey appearance on the edge, and then forming a safety bevel with that same second part. The combination tool of the invention avoids the need to remove the lens from the edger for polishing and safety beveling, thus minimizing handling and damage costs. Polishing of the edge by the polishing tool is facilitated by a water spray directed at the polishing tool. A vacuum removes the water droplets and lens blank particles from the interior of the edger cabinet, thus avoiding damage to electrical components and the like.